Audio Noise Suppression Filtering with Dynamic Minimum Gain
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Solution Overview
Problem
Existing audio signal processing techniques in full-duplex speech communication struggle to maintain optimal speech and noise levels, leading to reduced audio quality due to fixed minimum noise suppression filter values, which result in audible noise components and signal distortions.
Innovation Solution
An apparatus and method that dynamically adjust noise suppression filter values based on audio signal characteristics, ensuring they are greater than or equal to a minimum value, allowing for flexible noise suppression and automatic gain control to enhance speech intelligibility and comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fixed minimum noise suppression filter values are used, then noise suppression is simplified, but audio quality deteriorates due to audible noise components and signal distortions
Solution Approach 1:
The patent applies dynamics by making the minimum noise suppression filter values adjustable rather than fixed. The filter values are dynamically adapted based on audio signal characteristics, allowing the system to optimize noise suppression while preserving speech quality. This is achieved through a gain value that scales the minimum filter values according to the actual noise and speech levels in the input signal.
Solution Approach 2:
The patent changes the parameter of minimum noise suppression filter values from fixed to variable. By introducing a gain value that modifies the minimum filter values based on audio signal analysis, the system can adapt the filtering strength to match the actual noise conditions, thereby improving audio quality without excessive complexity.
2Object-affected harmful factors
If noise suppression filter values are increased to suppress noise, then noise attenuation improves, but speech quality deteriorates due to signal distortions
Solution Approach 1:
The patent uses parameter changes by introducing a gain value that scales the minimum noise suppression filter values. This gain is determined based on the ratio of noise level to speech level in the audio signal, allowing the filter strength to be proportional to the actual noise conditions. When noise is low, the filter values are reduced to preserve speech; when noise is high, the filter values are increased to suppress noise effectively.
Solution Approach 2:
The patent implements feedback by analyzing the audio signal characteristics (noise level, speech level) and using this information to adjust the minimum noise suppression filter values through the gain calculation. This closed-loop approach ensures that noise suppression is applied adaptively, suppressing noise when present while minimizing distortion to speech when noise levels are low.
3Object-affected harmful factors
If aggressive noise suppression is applied, then noise components are reduced, but listening comfort deteriorates due to unnatural audio output
Solution Approach 1:
The patent applies parameter changes by making the noise suppression filter values proportional to the gain, which is determined by the noise-to-speech level ratio. This ensures that noise suppression is applied at a natural level that matches the actual noise conditions, avoiding over-suppression that would create unnatural artifacts and maintain listening comfort.
Data Source
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AI summary
An apparatus for processing an audio signal comprises an audio signal analyzer and a filter. The audio signal analyzer is configured to analyze an audio signal to determine a plurality of noise suppression filter values for a plurality of bands of the audio signal, wherein the analyzer is configured to determine a noise suppression filter value so that a noise suppression filter value is greater than or equal to a minimum noise suppression filter value and so that the minimum noise suppression value depends on a characteristic of the audio signal. The filter is configured for filtering the audio signal, wherein the filter is adjusted based on the noise suppression filter values.